[clang] [CMAKE][AMDGPU] fix build failure caused by PR #133619 (PR #133776)

[Farzon Lotfi via cfe-commits]

farzonl wrote:

> @farzonl can you please revert the original commit? It seems to break just any LLVM build, so I guess the CI testing of all new PRs should be affected.

I don't see it breaking any build in LLVM, just the amd offload ones. Al the Premerge tests also passed.  I suspect the `AMDGPUBot.cmake` is doing something unique. Will study it more 

but the PR to revert is here https://github.com/llvm/llvm-project/pull/133795

https://github.com/llvm/llvm-project/pull/133776